Terahertz (THz) waves possess a number of unique capabilities and properties, including ones that make them useful for chemical identification, material characterization, biological sensing, and medical imaging, to cite a few examples. Terahertz Time Domain Spectroscopy (THz-TDS) is a spectroscopic technique that uses very short pulses of THz radiation to probe or analyze different properties of a material and is sensitive to the material's effect on both the amplitude and phase of the THz radiation. Although there is much potential for the commercial use of THz-TDS systems, their use thus far has been somewhat hindered by certain drawbacks, such as their low power, inefficiency, high cost, thermal breakdown, complexity, and the bulky nature of existing terahertz sources.
For example, most existing terahertz (THz) spectrometers are not broadly used for military and commercial chemical detection and/or characterization purposes. This is mainly due to the drawbacks mentioned above which can hinder the practical feasibility of such systems, particularly in portable systems. Some research has been conducted in the areas of frequency domain terahertz spectrometers utilizing coherent terahertz sources, solid-state terahertz sources, quantum-cascade lasers (QCLs), and nonlinear optical techniques for down-conversion to terahertz frequencies, to name a few, however, each of these approaches has drawbacks of its own. Finding an approach that offers suitable output power and efficiency across a wide range of terahertz (THz) or nearby frequencies, yet does so in a relatively compact form and under normal operating conditions, can be challenging.